body {
background-color: #000;
color: #fff;
font-family: sans-serif;
}
.board {
display: flex;
flex-direction: row;
justify-content: center;
align-items: center;
}
.square {
width: 100px;
height: 100px;
margin: 10px;
background-color: #fff;
color: #000;
font-size: 50px;
text-align: center;
cursor: pointer;
}
.square:hover {
background-color: #ccc;
}
.square.active {
background-color: #000;
color: #fff;
}
.winner {
background-color: #f00;
color: #fff;
}